Although alcohol clearly leads to alterations in mental processes and behavior, it is perhaps because these effects are so great and so pervasive that they have proven difficult to characterize. The global performance measures commonly used to document such effects clearly demonstrate their presence but often provide little information as to the specific locus or mechanism of effect. The present research aims to parse the separate effects of alcohol on peripheral nerve, sensory, cognitive, and motor systems, using event-related brain electrical potentials. These potentials are studied within a broad context provided by performance, psychophysiological, neuropsychological, neuroradiological, and neuropsychiatric data. The effects of alcohol are investigated in three classes of subjects: (1) normal volunteers, in whom the effects of acute administration are examined with respect to dose-response relationships, the temporal course of effect, and relationship to blood alcohol levels; (2) social drinkers, in whom brain electrical activity is studied, in conjunction with neuropsychological data, in an attempt to assay the effects of moderate levels of alcohol consumption; and (3) abstaining alcoholics (including those with alcoholism-related mental impairment) in whom deficits are characterized, short- and long-term recovery effects (if any) during abstinence are examined, and the efficacy of various treatment strategies is examined.